Five elderly singing group members have been injured after a man reportedly armed with a machete burst into a church hall.
An 84-year-old man was among those hurt during the incident in Orpington, south-east London, on Tuesday night.
Members of the group said a masked man with a Mohican haircut or wearing a wig broke into St Paul's Cray hall and staged a random attack.
The Met Police said a man, 56, had been arrested as part of investigations.
He was arrested on suspicion of assault and criminal damage was being treated in hospital for a hand injury, the police spokesman added.
Two women, one in her 80s, another aged about 60, and three men - one aged 84 and two in their 60s, have been injured, according to the Met.
"None of the injuries are believed to be serious and none were caused by the machete," the police spokesman added.
Ginny Warner, who had been singing in her local ladies' barbershop group, said a man "went to the vicar's driveway and was smashing up the vicar's car and then he started walking towards where we were.
"I was trying to peep through the curtains to describe him to the police on the phone without being noticed."
Ms Warner added that it took two passing strangers to bring the attack to a halt.
"A black guy who was a complete hero arrived and wrestled the guy on to the grass," she said.